With sequencing of the human genome completed, attention is focusing on understanding gene function, which for approximately half of all genes remains unknown. A crucial first step is to determine spatial and temporal patterns of gene expression. This is especially important for early stages of embryogenesis, when many important developmental processes occur and when genes critical for normal development are expressed. Since gene expression analysis in human embryos is ethically untenable, mapping of expression patterns must be accomplished in model organisms. Chicken is the premiere non-mammalian model organism, and is used in research across a broad spectrum of research disciplines. The chicken embryo provides many advantages for large-scale expression screening, including striking similarities to human, low expense and ready availability. The goal of this proposal is to create an in situ hybridization expression resource for chicken embryos. The objectives are as follows: 1) to expand an existing gene expression screening effort, called GEISHA (gallus est in situ hybridization analysis), using automated high throughput whole mount in situ hybridization analysis to map the location of expressed sequences in chick embryos through four days of development; 2) to acquire additional expression data through parallel coordinated screening efforts, from individual researchers, and from published results; 3) to house expression information in a relational database and present expression data to the research community using a freely accessible web interface. A chicken anatomical ontology will be created to describe expression patterns and to enable spatio-temporal querying, and data will be used to annotate the chicken genome. This centralized repository for in situ hybridization gene expression information will provide a valuable and comprehensive resource for the biomedical research community.